No unfortunately when you installed Windows 7 OEM on PC, it became tied to motherboard so you cannot move it to new motherboard if the original motherboard died or sold off in few years time. You will have to sell bundled Windows 7 OEM with motherboard.
If you had bought Windows 7 Retail and install on PC, it wont tied to motherboard so you can move it to new motherboard when you not used your current motherboard if it either died or sold off.